1. Field of the Invention
With reference to the classification of art as established in and by the United States Patent and Trademark Office this invention pertains to filter devices usually concerned with surgical procedures or with drainage devices used by people. The general class may be in "Surgery" or may be in "Liquid Purification or Separation". The filter means hereafter shown and described pertains to flexible tubular filters disposed within and spaced from the interior sidewalls of a tubular flexible conductor.
2. Description of the Prior Art
A search of the art revealed many filters disposed within flexible, impervious outer membranes. Of particular note is U.S. Pat. No. 3,506,130 as issued on Apr. 14, 1970 to SHAYE. This SHAYE embodiment requires manual venting and in this filter chamber a filter body is a substantially flat membrane and not Applicant's tubular membrane hereinafter described. U.S. Pat. No. 3,854,907 as issued Dec. 17, 1974 to RISING includes a housing and a filter membrane. The housing of RISING is rigid and the filter membrane is not a flexible member. In this instant invention the flexible filter is tubular and is disposed within a flexible tubular member such as I.V. tubing. U.S. Pat. No. 4,276,170 as issued June 30, 1981 to the Applicant shows a filter membrane in flat form in a housing. Construction of the filter is particularly shown in FIGS. 4, 5, 6 and 7. Also of note is U.S. Pat. No. 4,341,538 as issued July 27, 1982 to VADNAY et al. This is an I.V. filter in which the membrane is disposed at an angle within the chamber which is rigid. A low profile inline filter is shown in U.S. Pat. No. 4,400,277 as issued Aug. 23, 1983 to LEASON. This inline filter anticipates substantially rigid support of the tubular filter.
The filter system of this invention to be hereinafter more fully described contemplates a tubular filter membrane usually extruded and having the capability of excluding bacteria and the like. Conventionally this filter is used with tubing of rather small diameter such as I.V. conventionally sized or drainage tubing. The filter membrane is usually of plastic and through the process to be described is secured to a molded connecting device including luer lock connectors to I.V. tubing.
The present invention is mainly directed to a filter assembly providing a unique structure particularly useful in the filtering of parenteral fluids during the administration of such fluids. The manufacture of the assembly components provides a novel filter structure. In and with I.V. administration procedures the solution is usually filtered then proceeds through an extension set to a catheter to administration to the patient. The filter membrane is sized to remove bacteria and other contaminants that may be in the solution.
For the most part, the commercially known I.V. filters utilize a hard-rigid casing or envelope to provide the required strength and protection and to prevent unwanted and accidental damage to the filter. This is a significant limitation since patients having such filter units taped to their anatomy develop pressure sores should they lie on these filters for any significant period of time. Attempts have been made to develop flexible filters to overcome this drawback. A problem encountered with such flexible filters used with I.V. administration is that after a flow control clamp is closed (this clamp is positioned above the filter), after priming or filling the system, the fluid continues to flow because of the encasement housing of said filter. Where a flexible housing is used, the atmospheric pressure causes a collapse of the housing, resulting in a continued fluid flow or dribble. This continued flow or dribble causes spillage, loss of priming volume and a ready source of and for site contamination. Most importantly, this dribble breaks the sterile technique supplied by the present invention. A flow control valve or clamp when placed below the filter is not desirable for two prime reasons. First, it is desirable that the filter be placed as close to a patient or recipient as possible, and, second, a flow control device requires a rigid member(s) which is outside of the IV tubing and not only provides bulk, but also pressure points or areas which often irritate the skin of the patient when he or she accidentally rolls on top of the device. This is especially true of older or debilitated patients. The present invention does not present such problems.
Except for large rigid IV filters which utilize half their area to provide air venting, all IV filters are position sensitive. The present invention provides air venting regardless of position, and the air vent is made small in size and does not protrude to make an uncomfortable addition. Two means are presented for providing this air vent and both provide a hydrophobic membrane which acts as a barrier to bacteria and the like while passing air. The flexible filter of this invention is tubular in form and is small enough to be inserted and disposed within the flexible IV tubing. This IV tubing is characterized as being flexible and capable of being formed into a five-eighths inch (5/8") bend radius or larger without collapsing and has sufficient wall thickness. to prevent collapse when the tubing is empty. With the present invention, the flow control valve or clamp when shut off above the filter instantly stops fluid flow. Fluid is retained within the flexible filter housing and priming volume is maintained. With the present invention, dribble does not occur and is not present.